1. Field of the Invention
The present invention relates to a method of and an apparatus for forming electrodes on a substrate, for example, for forming electrodes within a photoelectric conversion surface of a substrate for photoelectric conversion element such as a solar cell substrate.
2. Description of the Related Art
As a technique for forming a predetermined pattern on a substrate, a pattern drawing technique on a substrate using an application liquid which contains a patterning material discharged from a nozzle is known. According to JP-A-2006-138911 for instance, a nozzle moving in one direction relative to a substrate discharges a paste-like patterning material which contains a photo-curing resin, thereby applying the patterning material to the substrate, irradiation of ultraviolet light hardens the resin, and a pattern is formed on the substrate. Further, according to this technique, gnarl portions having different pattern widths are formed at regular intervals as any one of the scanning speed, the discharge volume and the exposure volume is changed regularly while the nozzle scans the substrate.
It should be possible to apply this technique described in the patent publication mentioned above to formation of electrodes for a photoelectric conversion element such as a solar cell. According to JP-A-2005-353851 for example, a number of narrow and line-like (linear) electrodes called finger electrodes and wide electrodes called bus electrodes which cross the finger electrodes are formed in a photoelectric conversion surface of a solar cell.
When such electrodes crossing each other are formed as a result of application of an application liquid, the application liquid builds thick upon existing electrodes at the intersections with the electrodes, thereby making the top surfaces of the electrodes having different heights from each other. In the case of a solar cell for instance, a metal electrode foil attached to the top surfaces of the electrodes at a later step can therefore adhere only less tightly to the top surfaces of the electrodes, which is a problem that the device poorly performs and is less durable.